The best feeling, offensive lineman Nate Cadogan says, is when the floor shakes. His teammates heartily agree, and they talk over each other as they describe what it's like to max out on a squat or a power clean, and then drop the heavy barbell on the floor and feel the vibrations.

That's a new sensation for Penn State players who, until this year, primarily did weight training on machines. One set, each machine. To exhaustion.

But now they're doing squats for the first time since arriving on campus, learning the power cleans and jerks used by Olympic weightlifters, and flipping tires around - all in the name of functional strength training, which coach Craig Fitzgerald instituted when he arrived in January.

"It's just a lot more fun," Cadogan said. "You can really get your whole body into it."

The players have other reasons for enjoying the new program, in which they do multiple sets of each exercise.

Linebacker Gerald Hodges said that when he runs and cuts, he feels more explosive. Offensive lineman Bryan Davies has lost 70 pounds (with some diet help, too). Center Matt Stankiewitch, according to his teammates, developed enough muscles to size up to a XXXL T-shirt. (Asked to confirm, he laughed but he didn't deny.)

"I think it's going to pay great dividends for us," offensive lineman John Urschel said. "When you switch up your training regimen, you see great returns. Not saying that one way is better than the other, but I believe you just see great results when introduced to something."

That may be true. But strength-training experts say there arefar more important benefits to a program built around multiple sets of exercises with free weights and Olympic-style lifting:

• Developing speed. Lifting a barbell enables an athlete to accelerate and decelerate the speed of the movement, something that's impossible on a machine. And exercises such as squats and power cleans are explosive movements that increase power, which in turn increases speed. Those exercises can't be done on machines.

"It's much easier to do explosive training with free weights," said Gary Hunter, a strength-training expert and professor at the University of Alabama-Birmingham. "And since football is a power sport, development of power is very important. You also have much more flexibility as far as developing movements that might be specific to an actual sporting movement."

• Improving coordination and balance. Machines work each muscle individually. But on a football field, players don't use each muscle separately. Muscles and joints work in concert with each other.

Making a cut on the field, for example, requires ankles, knees, hips and all of the connecting muscles to move together. Free weights, unlike machines, build up the necessary neural connections.

Explained John Miller, assistant professor of kinesiology at Penn State and a certified athletic trainer: "If you train your muscle to work slow, if you train it in an isolated fashion, when you go to do a functional activity - run or cut or jump - the nervous system is not going to be able to contract the muscle at the right time with the right intensity and coordination with other muscles, as well."

"So maybe if I go out and block a linebacker this year, instead of maybe him hitting me and me falling over, maybe he hits me and my balance is good. So I can stay on my feet and still make the block."

• Reducing injuries. Training muscles and joints to work together reduces the chance that one muscle will be overtrained. An imbalance in muscle strength is one cause of injuries.

Machines have two other drawbacks. Athletes can make only one movement in one plane - machines don't allow for variation of movement - and that can lead to overuse injuries. And machines are designed for athletes to do one set of lifts to exhaustion, which increases the size of the muscle but doesn't necessarily build the density needed to absorb continual punishment.

While the correlation isn't absolute, some research has shown that exclusively training on machines may lead to a higher incidence of ACL tears.

"You're not training the muscles to coordinate with each other," Miller said. "One of the major reasons you tear your ACL is that if you're going to cut, your knee collapses to the inside. With the functional strength training going on now, the idea is if you dictate good form, the trunk, hip, knee and ankle all work together at the same time. It keeps the body in good alignment."

These benefits aren't breaking news. Miller said physical training facilities started to get rid of isokinetic knee machines, on which patients did leg extensions and presses to recover from knee injuries, in the late 1980s and 1990s.

Hunter said major college programs have been using functional strength training for the past 15 or 20 years. "I'm pretty surprised that Penn State was using a foundation that was machines," he said.

Sixty years ago, few football players trained with weights. Strength training had a bad reputation among coaches, Hunter said, dating back to the late 1890s, when the "old-time strength men" promoted their mail-order training programs by warning prospective clients away from barbells, which would make athletes slow and burdened by oversized muscles.

Unlike the programs hawked by the strongmen, of course. "The analogy," said Hunter, "was 'Do you want to be a thoroughbred horse or a draft horse?'"

Not until the 1970s, he said, was weight training - with barbells and other free weights - common for football teams. Then, late in the decade, Arthur Jones invented the Nautilus machine and introduced his philosophy of high-intensity, slow-movement training.

Nautilus machines had new technology, specifically a new cam and a variable resistance apparatus, that Jones said allowed a muscle to be worked through its full range of motion like never before. He also said that by working slowly through the range of motion - raised in two seconds, lowered in four - muscles would get stronger and bigger than ever before possible.

"He said you only had to do one set to exhaustion, and you're Superman," Hunter said. "They really sold a bill of goods to strength coaches."

That wasn't apparent at the time, and coaches embraced the machines. Needing to work only one set of each exercise allowed players to spend more time practicing and studying the playbook.

But research began to show that old-fashioned weight training - barbells, free weights, Olympic-style lifting - did a better overall job of building strength. Or, as Hunter put it: Nautilus was "all a bunch of hogwash."

The trend moved to "functional" training, which mimics everyday movement and not only increases the size of a muscle, but increases a muscle's ability to work with other muscles. Machines still have their uses, but not to achieve peak performance.Fitzgerald won't comment on Penn State's previous weight training regimen. "I don't know what they did," he said.

He's happy to talk about his own, though. When Fitzgerald arrived, he essentially gutted the weight room and installed dozens of free-weight stations. Now all but two of the team's weight exercises are performed standing - "as much as you can do on your feet," he said, "because that's how the game is."

There's also a giant sand pit - possibly the largest in the country, he said, at 50 yards by 20 yards - at the outdoor track. That allows players to strengthen their ankles and the rest of their legs as they run.

Fitzgerald learned about strength training when he played at Maryland, where his strength coach was Dwight Galton. He later worked for Galt (and Galt's son, Dwight IV, known as "Deege," worked for him at South Carolina and followed him to Penn State). Football coaches may once have worried that too much muscle would hinder speed, but Fitzgerald has always known that muscle is necessary for speed.

"I think the people who were on the cutting edge, the people who knew what they were doing, always felt like weight training was the way to go as part of a speed program," he said. "Not the only thing... They go hand in hand."

Penn State's players didn't have much experience with free weights, so Fitzgerald and his staff started slowly, perfecting technique before adding weight. Even now, Fitzgerald stresses that technique is vital by making sure that the first set of every exercise is with the bar only. The second set has only a light weight.

"We work up to top weight, but we don't try to max out every day," he said. "A good day for us is to get them in there and working hard, get good weight on the bar for working sets - and to be able to train hard and train well the next day, too."

Each week follows basically the same pattern:Monday is "speed and power day." Or, as Fitzgerald also calls it, "training for pro combine, really." He thinks if players improve in the 40-yard dash, the shuttle, the three-cone, and the broad and vertical jumps, they'll be better football players.

Tuesday is "upper body day." Or, as Fitzgerald also calls it, "old-school kick-your-butt conditioning day." Once they're out of the gym, then it's a big yardage day - 400-, 200-, 100- and 60-yard shuttles.

"We leave 'em weeping that day," Fitzgerald said. "Big Tuesday."

The players come back Thursday for hill running, sand pit workouts and resistance training, a little lighter on the legs.

Friday is the only day the team lifts together. Fitzgerald has organized a competition, with the players divided into teams for tug of war, bar pushing, farmers' carry - the kind of activities the public sees at Lift for Life.

"Our job is to maximize every player," Fitzgerald said. "We don't think about who the player is or what the newspapers say or even how the football coaches grade them on the depth chart. We don't care. That's not our job. Our job is to train the living heck out of them.

"The guy could be a valuable member of the scout team for four years and then go on and become a great member of our whole society, a great dad. We take a fifth-teamer, he may be first team in four years. We may have a first-teamer make All-American. And if we have more walk-ons than we've had, we're going to make them the best players they can be. Maybe they're hidden gems. Everybody matters."